Controlled release oxycodone compositions

ABSTRACT

A method for substantially reducing the range in daily dosages required to control pain in approximately 90% of patients is disclosed whereby an oral solid controlled release dosage formulation having from about 10 to about 40 mg of oxycodone or a salt thereof is administered to a patient. The formulation provides a mean maximum plasma concentration of oxycodone from about 6 to about 60 ng/ml from a mean of about 2 to about 4.5 hours after administration, and a mean minimum plasma concentration from about 3 to about 30 ng/ml from about 10 to about 14 hours after repeated &#34;q12h&#34; (i.e., every 12 hour) administration through steady-state conditions. Another embodiment is directed to a method for substantially reducing the range in daily dosages required to control pain in substantially all patients by administering an oral solid controlled release dosage formulation comprising up to about 160 mg of oxycodone or a salt thereof, such that a mean maximum plasma concentration of oxycodone up to about 240 ng/ml from a mean of up to about 2 to about 4.5 hours after administration, and a mean minimum plasma concentration up to about 120 ng/ml from about 10 to about 14 hours after repeated &#34;q12h&#34; (i.e., every 12 hour) administration through steady-state conditions are achieved. Controlled release oxycodone formulations for achieving the above are also disclosed.

This application is a continuation of Ser. No. 08/081,302, filed Jun.18, 1993, now U.S. Pat. No. 5,549,912, which is a continuation-in-partof Ser. No. 07/800,549, filed Nov. 27, 1991, now U.S. Pat. No.5,266,331.

BACKGROUND OF THE INVENTION

Surveys of daily dosages of opioid analgesics required to control painsuggest that an approximately eight-fold range in daily dosages isrequired to control pain in approximately 90% of patients. Thisextraordinary wide range in the appropriate dosage makes the titrationprocess particularly time consuming and resource consuming, as well asleaving the patient without acceptable pain control for an unacceptablylong duration.

In the management of pain with opioid analgesics, it has been commonlyobserved and reported that there is considerable inter-individualvariation in the response to a given dose of a given drug, and,therefore, considerable variability among patients in the dosage ofopioid analgesic required to control pain without unacceptable sideeffects. This necessitates considerable effort on the part of cliniciansin establishing the appropriate dose in an individual patient throughthe time consuming process of titration, which requires carefulassessment of both therapeutic and side effects and dosage adjustmentsover a period of days and sometimes longer before the appropriate dosageis determined. The American Pain Society's 3rd Edition of Principles ofAnalgesic Use in the Treatment of Acute Pain and Cancer Pain explainsthat one should "be aware that the optimal analgesic dose varies widelyamong patients. Studies have shown that in all age groups, there isenormous variability in doses of opioids required to provide relief,even among opioid naive patients with identical surgical lesions . . . .This great variability underscores the need to write analgesic ordersthat include provision for supplementary doses, and to use intravenousboluses and infusions to provide rapid relief of severe pain . . . .Give each analgesic an adequate trial by dose titration . . . beforeswitching to another drug."

An opioid analgesic treatment which acceptably controls pain over asubstantially narrower daily dosage range would, therefore,substantially improve the efficiency and quality of pain management.

It has previously been known in the art that controlled releasecompositions of opioid analgesics such as morphine, hydromorphone orsalts thereof could be prepared in a suitable matrix. For example, U.S.Pat. No. 4,990,341 (Goldie), also assigned to the assignee of thepresent invention, describes hydromorphone compositions wherein thedissolution rate in vitro of the dosage form, when measured by the USPPaddle Method at 100 rpm in 900 ml aqueous buffer (pH between 1.6 and7.2) at 37° C., is between 12.5 and 42.5% (by wt) hydromorphone releasedafter 1 hour, between 25 and 55% (by wt) released after 2 hours, between45 and 75% (by wt) released after 4 hours and between 55 and 85% (by wt)released after 6 hours.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method forsubstantially improving the efficiency and quality of pain management.

It is another object of the present invention to provide an opioidanalgesic formulation which substantially improves the efficiency andquality of pain management.

It is another object of the present invention to provide a method andformulation(s) which substantially reduce the approximately eight-foldrange in daily dosages required to control pain in approximately 90% ofpatients.

It is another object of the present invention to provide a method andformulation(s) which substantially reduce the variability in dailydosages and formulation requirements necessary to control pain insubstantially all patients.

It is yet another object of the present invention to provide a methodfor substantially reducing the time and resources need to titratepatients requiring pain relief on opioid analgesics.

It is yet another object of the present invention to provide controlledrelease opioid formulations which have substantially lessinter-individual variation with regard to the dose of opioid analgesicrequired to control pain without unacceptable side effects.

The above objects and others are attained by virtue of the presentinvention, which is related to a solid controlled release oral dosageform, the dosage form comprising from about 10 to about 40 mg ofoxycodone or a salt thereof in a matrix wherein the dissolution rate invitro of the dosage form, when measured by the USP Paddle Method at 100rpm in 900 ml aqueous buffer (pH between 1.6 and 7.2) at 37° C. isbetween 12.5 and 42.5% (by wt) oxycodone released after 1 hour, between25 and 56% (by wt) oxycodone released after 2 hours, between 45 and 75%(by wt) oxycodone released after 4 hours and between 55 and 85% (by wt)oxycodone released after 6 hours, the in vitro release rate beingsubstantially independent of pH, such that the peak plasma level ofoxycodone obtained in vivo occurs between 2 and 4.5 hours afteradministration of the dosage form.

USP Paddle Method is the Paddle Method described, e.g., in U.S.Pharmacopoeia XXII (1990).

In the present specification, "substantially independent of pH" meansthat the difference, at any given time, between the amount of oxycodonereleased at, e.g., pH 1.6, and the amount released at any other pH,e.g., pH 7.2 (when measured in vitro using the USP Paddle Method at 100rpm in 900 ml aqueous buffer), is 10% (by weight) or less. The amountsreleased being, in all cases, a mean of at least three experiments.

The present invention is further related to a method for substantiallyreducing the range in daily dosages required to control pain inapproximately 90% of patients, comprising administering an oral solidcontrolled release dosage formulation comprising from about 10 to about40 mg of oxycodone or a salt thereof, said formulation providing a meanmaximum plasma concentration of oxycodone from about 6 to about 60 ng/mlfrom a mean of about 2 to about 4.5 hours after administration, and amean minimum plasma concentration from about 3 to about 30 ng/ml from amean of about 10 to about 14 hours after repeated "q12h" (i.e., every 12hour) administration through steady-state conditions.

The present invention is further related to a method for substantiallyreducing the range in daily dosages required to control pain insubstantially all patients, comprising administering an oral solidcontrolled release dosage formulation comprising up to about 160 mg ofoxycodone or a salt thereof, said formulation providing a mean maximumplasma concentration of oxycodone up to about 240 ng/ml from a mean ofup to about 2 to about 4.5 hours after administration, and a meanminimum plasma concentration up to about 120 ng/ml from a mean of about10 to about 14 hours after repeated "q12h" (i.e., every 12 hour)administration through steady-state conditions.

The present invention is further related to controlled release oxycodoneformulations comprising from about 10 to about 40 mg oxycodone or a saltthereof, said formulations providing a mean maximum plasma concentrationof oxycodone from about 6 to about 60 ng/ml from a mean of about 2 toabout 4.5 hours after administration, and a mean minimum plasmaconcentration from about 3 to about 30 ng/ml from about 10 to about 14hours after repeated q12h administration through steady-stateconditions.

The present invention is further related to controlled release oxycodoneformulations comprising up to about 160 mg oxycodone or a salt thereof,said formulations providing a mean maximum plasma concentration ofoxycodone up to about 240 ng/ml from a mean of about 2 to about 4.5hours after administration, and a mean minimum plasma concentration upto about 120 ng/ml from about 10 to about 14 hours after repeated q12hadministration through steady-state conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the inventionand are not meant to limit the scope of the invention as encompassed bythe claims.

FIGS. 1-4 are graphs showing the time-effect curves for pain intensitydifferences and pain relief for Example 17;

FIG. 5 is a graph showing the mean plasma oxycodone concentration for a10 mg controlled release oxycodone formulation prepared in accordancewith the present invention and a study reference standard.

DETAILED DESCRIPTION

It has now been surprisingly discovered that the presently claimedcontrolled release oxycodone formulations acceptably control pain over asubstantially narrower, approximately four-fold (10 to 40 mg every 12hours--around-the-clock dosing) in approximately 90% of patients. Thisis in sharp contrast to the approximately eight-fold range required forapproximately 90% of patients for opioid analgesics in general.

The use of from about 10 mg to about 40 mg of 12-hourly doses ofcontrolled-release oxycodone to control pain in approximately 90% ofpatients relative to a wider dosage range of other μ-agonist analgesics,indicated for moderate to severe pain, is an example of the uniquecharacteristics of the present invention. It should also be appreciatedthat the remaining 10% of patients would also be successfully managedwith 12-hourly controlled-release oxycodone over a relatively narrowerdosage range than with the use of other similar analgesics.Substantially all of those remaining 10% of patients not managed withcontrolled release oxycodone, 10 mg to 40 mg every 12 hours, would bemanaged using dosages of greater than 40 mg every 12 hours through 160mg every 12 hours utilizing any one of a number or multiples offormulation strengths such as 10, 20, 40, 80 and 160 mg unit dosages orcombinations thereof. In contrast, the use of other similar analgesicssuch as morphine would require a wider range of dosages to manage theremaining 10% of patients. For example, daily dosages of oral morphineequivalents in the range of 1 gram to more than 20 grams have beenobserved. Similarly, wide dosage ranges of oral hydromorphone would alsobe required.

Morphine, which is considered to be the prototypic opioid analgesic, hasbeen formulated into a 12 hour controlled-release formulations (i.e., MSContin® tablets, commercially available from Purdue Pharma, L.P.).Despite the fact that both controlled-release oxycodone and controlledrelease morphine administered every 12 hours around-the-clock possessqualitatively comparable clinical pharmacokinetic characteristics, theoxycodone formulations of the presently claimed invention can be usedover approximately 1/2 the dosage range as compared to commerciallyavailable controlled release morphine formulations (such as MS Contin®)to control 90% of patients with significant pain.

Repeated dose studies with the controlled release oxycodone formulationsadministered every 12 hours in comparison with immediate release oraloxycodone administered every 6 hours at the same total daily dose resultin comparable extent of absorption, as well as comparable maximum andminimum concentrations. The time of maximum concentration occurs atapproximately 2-4.5 hours after oral administration with thecontrolled-release product as compared to approximately 1 hour with theimmediate release product. Similar repeated dose studies with MS Contin®tablets as compared to immediate release morphine provide for comparablerelative results as with the controlled release oxycodone formulationsof the present invention.

There exists no substantial deviation from parallelism of thedose-response curves for oxycodone either in the forms of the controlledrelease oxycodone formulations of the present invention, immediaterelease oral oxycodone or parenteral oxycodone in comparison with oraland parenteral opioids with which oxycodone has been compared in termsof dose-response studies and relative analgesic potency assays. Beaver,et al., "Analgesic Studies of Codeine and Oxycodone in Patients withCancer. II. Comparisons of Intramuscular Oxycodone with IntramuscularMorphine and Codeine", J. Pharmacol. and Exp. Ther., Vol. 207, No. 1,pp. 101-108, reported comparable dose-response slopes for parenteraloxycodone as compared to parenteral morphine and comparabledose-response slopes for oral as compared to parenteral oxycodone.

A review of dose-response studies and relative analgesic assays ofmu-agonist opioid analgesics, which include oxycodone, morphine,hydromorphone, levorphanol, methadone, meperidine, heroin, all indicateno significant deviation from parallelism in their dose responserelationships. This is so well established that it has become anunderlining principal providing for establishing relative analgesicpotency factors and dose ratios which are commonly utilized whenconverting patients from one mμ-agonist analgesic to another regardlessof the dosage of the former. Unless the dose-response curves areparallel, conversion factors would not be valid across the wide range ofdosages involved when substituting one drug for another.

The clinical significance provided by the controlled release oxycodoneformulations of the present invention at a dosage range from about 10 toabout 40 mg every 12 hours for acceptable pain management inapproximately 90% of patients with moderate to severe pain, as comparedto other opioid analgesics requiring approximately twice the dosagerange provides for the most efficient and humane method of managing painrequiring repeated dosing. The expertise and time of physicians andnurses, as well as the duration of unacceptable pain patients mustendure during the opioid analgesic titration process is substantiallyreduced through the efficiency of the controlled release oxycodoneformulations of the present invention.

It is further clinically significant that a dose of about 80 mgcontrolled release oxycodone administered every 12 hours will provideacceptable pain relief management in, e.g., approximately 95% ofpatients with moderate to severe pain, and that about 160 mg controlledrelease oxycodone administered every 12 hours will provide acceptablepain relief management in, e.g., approximately all patients withmoderate to severe pain.

In order to obtain a controlled release drug dosage form having at leasta 12 hour therapeutic effect, it is usual in the pharmaceutical art toproduce a formulation that gives a peak plasma level of the drug betweenabout 4-8 hours after administration (in a single dose study). Thepresent inventors have surprisingly found that, in the case ofoxycodone, a peak plasma level at between 2-4.5 hours afteradministration gives at least 12 hours pain relief and, mostsurprisingly, that the pain relief obtained with such a formulation isgreater than that achieved with formulations giving peak plasma levels(of oxycodone) in the normal period of up to 2 hours afteradministration.

A further advantage of the present composition, which releases oxycodoneat a rate that is substantially independent of pH, is that it avoidsdose dumping upon oral administration. In other words, the oxycodone isreleased evenly throughout the gastrointestinal tract.

The present oral dosage form may be presented as, for example, granules,spheroids or pellets in a capsule or in any other suitable solid form.Preferably, however, the oral dosage form is a tablet.

The present oral dosage form preferably contains between 1 and 500 mg,most especially between 10 and 160 mg, of oxycodone hydrochloride.Alternatively, the dosage form may contain molar equivalent amounts ofother oxycodone salts or of the oxycodone base.

The present matrix may be any matrix that affords in vitro dissolutionrates of oxycodone within the narrow ranges required and that releasesthe oxycodone in a pH independent manner. Preferably the matrix is acontrolled release matrix, although normal release matrices having acoating that controls the release of the drug may be used. Suitablematerials for inclusion in a controlled release matrix are

(a) Hydrophilic polymers, such as gums, cellulose ethers, acrylic resinsand protein derived materials. Of these polymers, the cellulose ethers,especially hydroxyalkylcelluloses and carboxyalkylcelluloses, arepreferred. The oral dosage form may contain between 1% and 80% (byweight) of at least one hydrophilic or hydrophobic polymer.

(b) Digestible, long chain (C₈ -C₅₀, especially C₁₂ -C₄₀), substitutedor unsubstituted hydrocarbons, such as fatty acids, fatty alcohols,glyceryl esters of fatty acids, mineral and vegetable oils and waxes.Hydrocarbons having a melting point of between 25° and 90° C. arepreferred. Of these long chain hydrocarbon materials, fatty (aliphatic)alcohols are preferred. The oral dosage form may contain up to 60% (byweight) of at least one digestible, long chain hydrocarbon.

(c) Polyalkylene glycols. The oral dosage form may contain up to 60% (byweight) of at least one polyalkylene glycol.

One particular suitable matrix comprises at least one water solublehydroxyalkyl cellulose, at least one C₁₂ -C₃₆, preferably C₁₄ -C₂₂,aliphatic alcohol and, optionally, at least one polyalkylene glycol.

The at least one hydroxyalkyl cellulose is preferably a hydroxy (C₁ toC₆) alkyl cellulose, such as hydroxypropylcellulose,hydroxypropylmethylcellulose and, especially, hydroxyethyl cellulose.The amount of the at least one hydroxyalkyl cellulose in the presentoral dosage form will be determined, inter alia, by the precise rate ofoxycodone release required. Preferably however, the oral dosage formcontains between 5% and 25%, especially between 6.25% and 15% (by wt) ofthe at least one hydroxyalkyl cellulose.

The at least one aliphatic alcohol may be, for example, lauryl alcohol,myristyl alcohol or stearyl alcohol. In particularly preferredembodiments of the present oral dosage form, however, the at least onealiphatic alcohol is cetyl alcohol or cetostearyl alcohol. The amount ofthe at least one aliphatic alcohol in the present oral dosage form willbe determined, as above, by the precise rate of oxycodone releaserequired. It will also depend on whether at least one polyalkyleneglycol is present in or absent from the oral dosage form. In the absenceof at least one polyalkylene glycol, the oral dosage form preferablycontains between 20% and 50% (by wt) of the at least one aliphaticalcohol. When at least one polyalkylene glycol is present in the oraldosage form, then the combined weight of the at least one aliphaticalcohol and the at least one polyalkylene glycol preferably constitutesbetween 20% and 50% (by wt) of the total dosage.

In one preferred embodiment, the controlled release compositioncomprises from about 5 to about 25% acrylic resin and from about 8 toabout 40% by weight aliphatic alcohol by weight of the total dosageform. A particularly preferred acrylic resin comprises Eudragit® RS PM,commercially available from Rohm Pharma.

In the present preferred dosage form, the ratio of, e.g., the at leastone hydroxyalkyl cellulose or acrylic resin to the at least onealiphatic alcohol/polyalkylene glycol determines, to a considerableextent, the release rate of the oxycodone from the formulation. A ratioof the at least one hydroxyalkyl cellulose to the at least one aliphaticalcohol/polyalkylene glycol of between 1:2 and 1:4 is preferred, with aratio of between 1:3 and 1:4 being particularly preferred.

The at least one polyalkylene glycol may be, for example, polypropyleneglycol or, which is preferred, polyethylene glycol. The number averagemolecular weight of the at least one polyalkylene glycol is preferredbetween 1000 and 15000 especially between 1500 and 12000.

Another suitable controlled release matrix would comprise analkylcellulose (especially ethyl cellulose), a C₁₂ to C₃₆ aliphaticalcohol and, optionally, a polyalkylene glycol.

In addition to the above ingredients, a controlled release matrix mayalso contain suitable quantities of other materials, e.g. diluents,lubricants, binders, granulating aids, colorants, flavorants andglidants that are conventional in the pharmaceutical art.

As an alternative to a controlled release matrix, the present matrix maybe a normal release matrix having a coat that controls the release ofthe drug. In particularly preferred embodiments of this aspect of theinvention, the present dosage form comprises film coated spheroidscontaining active ingredient and a non-water soluble spheronising agent.The term spheroid is known in the pharmaceutical art and means aspherical granule having a diameter of between 0.5 mm and 2.5 mmespecially between 0.5 mm and 2 mm.

The spheronising agent may be any pharmaceutically acceptable materialthat, together with the active ingredient, can be spheronised to formspheroids. Microcrystalline cellulose is preferred.

A suitable microcrystalline cellulose is, for example, the material soldas Avicel PH 101 (Trade Mark, FMC Corporation). According to a preferredaspect of the present invention, the film coated spheroids containbetween 70% and 99% (by wt), especially between 80% and 95% (by wt), ofthe spheronising agent, especially microcrystalline cellulose.

In addition to the active ingredient and spheronising agent, thespheroids may also contain a binder. Suitable binders, such as lowviscosity, water soluble polymers, will be well known to those skilledin the pharmaceutical art. However, water soluble hydroxy lower alkylcellulose, such as hydroxy propyl cellulose, are preferred. Additionally(or alternatively) the spheroids may contain a water insoluble polymer,especially an acrylic polymer, an acrylic copolymer, such as amethacrylic acid-ethyl acrylate copolymer, or ethyl cellulose.

The spheroids are preferably film coated with a material that permitsrelease of the oxycodone (or salt) at a controlled rate in an aqueousmedium. The film coat is chosen so as to achieve, in combination withthe other ingredients, the in-vitro release rate outlined above (between12.5% and 42.5% (by wt) release after 1 hour, etc.).

The film coat will generally include a water insoluble material such as

(a) a wax, either alone or in admixture with a fatty alcohol,

(b) shellac or zein,

(c) a water insoluble cellulose, especially ethyl cellulose,

(d) a polymethacrylate, especially Eudragit®.

Preferably, the film coat comprises a mixture of the water insolublematerial and a water soluble material. The ratio of water insoluble towater soluble material is determined by, amongst other factors, therelease rate required and the solubility characteristics of thematerials selected.

The water soluble material may be, for example, polyvinylpyrrolidone or,which is preferred, a water soluble cellulose, especiallyhydroxypropylmethyl cellulose.

Suitable combinations of water insoluble and water soluble materials forthe film coat include shellac and polyvinylpyrrolidone or, which ispreferred, ethyl cellulose and hydroxypropylmethyl cellulose.

In order to facilitate the preparation of a solid, controlled release,oral dosage form according to this invention there is provided, in afurther aspect of the present invention, a process for the preparationof a solid, controlled release, oral dosage form according to thepresent invention comprising incorporating oxycodone or a salt thereofin a controlled release matrix. Incorporation in the matrix may beeffected, for example, by

(a) forming granules comprising at least one water soluble hydroxyalkylcellulose and oxycodone or a oxycodone salt,

(b) mixing the hydroxyalkyl cellulose containing granules with at leastone C₁₂ -C₃₆ aliphatic alcohol, and

(c) optionally, compressing and shaping the granules. Preferably, thegranules are formed by wet granulating the hydroxyalkylcellulose/oxycodone with water. In a particularly preferred embodimentof this process, the amount of water added during the wet granulationstep is preferably between 1.5 and 5 times, especially between 1.75 and3.5 times, the dry weight of the oxycodone.

The present solid, controlled release, oral dosage form may also beprepared, in the form of film coated spheroids, by

(a) blending a mixture comprising oxycodone or a oxycodone salt and anon-water soluble spheronising agent,

(b) extruding the blended mixture to give an extrudate,

(c) spheronising the extrudate until spheroids are formed, and

(d) coating the spheroids with a film coat.

The present solid, controlled release, oral dosage form and processesfor its preparation will now be described by way of example only.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples illustrate various aspects of the presentinvention. They are not meant to be construed to limit the claims in anymanner whatsoever.

EXAMPLE 1 Controlled Release Oxycodone HCl 30 mg Tablets--AqueousManufacture

The required quantities of oxycodone hydrochloride, spray-dried lactose,and Eudragit® RS PM are transferred into an appropriate-size mixer, andmixed for approximately 5 minutes. While the powders are mixing, themixture is granulated with enough water to produce a moist granularmass. The granules are then dried in a fluid bed dryer at 60° C., andthen passed through an 8-mesh screen. Thereafter, the granules areredried and pushed through a 12-mesh screen. The required quantity ofstearyl alcohol is melted at approximately 60°-70° C., and while thegranules are mixing, the melted stearyl alcohol is added. The warmgranules are returned to the mixer.

The coated granules are removed from the mixer and allowed to cool. Thegranules are then passed through a 12-mesh screen. The granulate is thenlubricated by mixing the required quantity of talc and magnesiumstearate in a suitable blender. Tablets are compressed to 375 mg inweight on a suitable tableting machine. The formula for the tablets ofExample 1 is set forth in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Formula of Oxycodone HCl 30-mg Tablets                                        Component         mg/Tablet                                                                              % (by wt)                                          ______________________________________                                        Oxycodone Hydrochloride                                                                         30.0      8                                                 Lactose (spray-dried)                                                                           213.75   57                                                 Eudragit ® RS PM                                                                            45.0     12                                                 Purified Water    q.s*     --                                                 Stearyl Alcohol   75.0     20                                                 Talc               7.5      2                                                 Magnesium Stearate                                                                               3.75     1                                                 Total:            375.0    100                                                ______________________________________                                         *Used in manufacture and remains in final product as residual quantity        only.                                                                    

The tablets of Example 1 are then tested for dissolution via the USPBasket Method, 37° C., 100 RPM, first hour 700 ml gastric fluid at pH1.2, then changed to 900 ml at 7.5. The results are set forth in Table 2below:

                  TABLE 2                                                         ______________________________________                                        Dissolution of Oxycodone 30 mg Controlled Release Tablets                     Time       % Oxycodone Dissolved                                              ______________________________________                                        1          33.1                                                               2          43.5                                                               4          58.2                                                               8          73.2                                                               12         81.8                                                               18         85.8                                                               24         89.2                                                               ______________________________________                                    

EXAMPLE 2 Controlled Oxycodone HCl 10 mg Release Tablets--OrganicManufacture

The required quantities of oxycodone hydrochloride and spray driedlactose are transferred into an appropriate sized mixer and mix forapproximately 6 minutes. Approximately 40 percent of the requiredEudragit® RS PM powder is dispersed in Ethanol. While the powders aremixing, the powders are granulated with the dispersion and the mixingcontinued until a moist granular mass is formed. Additional ethanol isadded if needed to reach granulation end point. The granulation istransferred to a fluid bed dryer and dried at 30° C.; and then passedthrough a 12-mesh screen. The remaining Eudragit® RS PM is dispersed ina solvent of 90 parts ethanol and 10 parts purified water; and sprayedonto the granules in the fluid bed granulator/dryer at 30° C. Next, thegranulate is passed through a 12-mesh screen. The required quantity ofstearyl alcohol is melted at approximately 60°-70° C. The warm granulesare returned to the mixer. While mixing, the melted stearyl alcohol isadded. The coated granules are removed from the mixer and allowed tocool. Thereafter, they are passed through a 12-mesh screen.

Next, the granulate is lubricated by mixing the required quantities oftalc and magnesium stearate in a suitable blender. The granulate is thencompressed to 125 mg tablets on a suitable tableting machine.

The formula for the tablets of Example 2 (10 mg controlled releaseoxycodone) is set forth in Table 3 below:

                  TABLE 3                                                         ______________________________________                                        Formula of Oxycodone HCl 10 mg Controlled Release Tablets                                                Percent                                            Component        Mg/Tablet (by wt)                                            ______________________________________                                        Oxycodone hydrochloride                                                                        10.00          8                                             Lactose (spray-dried)                                                                          71.25         57                                             Eudragit ® RS PM                                                                           15.00         12                                             Ethanol          q.s.*         --                                             Purified Water   q.s.*         --                                             Stearyl Alcohol  25.00         20                                             Talc             2.50           2                                             Magnesium stearate                                                                             1.25           1                                             Total:           125.00  mg    100                                            ______________________________________                                         *Used only in the manufacture and remains in final product as residual        quantity only.                                                           

The tablets of Example 2 are then tested for dissolution via USP BasketMethod at 37° C., 100 RPM, first hour 700 ml simulated gastric (pH 1.2)then changed to ml at pH 7.5.

The results are set forth in Table 4 below:

                  TABLE 4                                                         ______________________________________                                        Dissolution of Oxycodone 10 mg Controlled Release Tablets                            Hour % Dissolved                                                       ______________________________________                                               1    35.9                                                                     2    47.7                                                                     4    58.5                                                                     8    67.7                                                                     12   74.5                                                                     18   76.9                                                                     24   81.2                                                              ______________________________________                                    

EXAMPLES 3-4 Controlled Release Oxycodone 10 and 20 mg Tablets (AqueousManufacture)

Eudragit® RS 30D and Triacetin® are combined while passing though a 60mesh screen, and mixed under low shear for approximately 5 minutes oruntil a uniform dispersion is observed.

Next, suitable quantities of Oxycodone HCl, lactose, and povidone areplaced into a fluid bed granulator/dryer (FBD) bowl, and the suspensionsprayed onto the powder in the fluid bed. After spraying, thegranulation is passed through a #12 screen if necessary to reduce lumps.The dry granulation is placed in a mixer.

In the meantime, the required amount of stearyl alcohol is melted at atemperature of approximately 70° C. The melted stearyl alcohol isincorporated into the granulation while mixing. The waxed granulation istransferred to a fluid bed granulator/dryer or trays and allowed to coolto room temperature or below. The cooled granulation is then passedthrough a #12 screen. Thereafter, the waxed granulation is placed in amixer/blender and lubricated with the required amounts of talc andmagnesium stearate for approximately 3 minutes, and then the granulateis compressed into 125 mg tablets on a suitable tableting machine.

The formula for the tablets of Example 3 is set forth in Table 5 below:

                  TABLE 5                                                         ______________________________________                                        Formula of Controlled Release Oxycodone 10 mg Tablets                         Component          Mg/Tablet                                                                              % (by wt)                                         ______________________________________                                        Oxycodone Hydrochloride                                                                          10.0     8.0                                               Lactose (spray dried)                                                                             69.25   55.4                                              Povidone            5.0     4.0                                               Eudragit ® RS 30D (solids)                                                                    10.0*   8.0                                               Triacetin ®     2.0     1.6                                               Stearyl Alcohol    25.0     20.0                                              Talc                2.5     2.0                                               Magnesium Stearate  1.25    1.0                                               Total:             125.0    100.0                                             ______________________________________                                         *Approximately 33.33 mg Eudragit ® RS 30D Aqueous dispersion is           equivalent to 10 mg of Eudragit ® RS 30D dry substance.              

The tablets of Example 3 are then tested for dissolution via the USPBasket Method at 37° C., 100 RPM, first hour 700 ml simulated gastricfluid at pH 1.2, then changed to 900 ml at pH 7.5. The results are setforth in Table 6 below:

                  TABLE 6                                                         ______________________________________                                        Dissolution of Oxycodone 10 mg Controlled Release Tablets                     Hour       % Oxycodone Dissolved                                              ______________________________________                                        1          38.0                                                               2          47.5                                                               4          62.0                                                               8          79.8                                                               12         91.1                                                               18         94.9                                                               24         98.7                                                               ______________________________________                                    

The formula for the tablets of Example 4 is set forth in Table 7 below:

                  TABLE 7                                                         ______________________________________                                        Formula of Controlled Release Oxycodone 20 mg Tablets                         Component          Mg/Tablet                                                  ______________________________________                                        Oxycodone Hydrochloride                                                                          20.0                                                       Lactose (spray dried)                                                                             59.25                                                     Povidone            5.0                                                       Eudragit ® RS 30D (solids)                                                                    10.0*                                                     Triacetin ®     2.0                                                       Stearyl Alcohol    25.0                                                       Talc                2.5                                                       Magnesium Stearate  1.25                                                      Total:             125.0                                                      ______________________________________                                    

The tablets of Example 4 are then tested for dissolution via the USPBasket Method at 37° C., 100 RPM, first hour 700 ml simulated gastricfluid at pH 1.2, then changed to 900 ml at pH 7.5. The results are setforth in Table 8 below:

                  TABLE 8                                                         ______________________________________                                        Dissolution of Oxycodone 20 mg Controlled Release Tablets                     Hour       % Oxycodone Dissolved                                              ______________________________________                                        1          31                                                                 2          44                                                                 4          57                                                                 8          71                                                                 12         79                                                                 18         86                                                                 24         89                                                                 ______________________________________                                    

EXAMPLES 5-6

In Example 5, 30 mg controlled release oxycodone hydrochloride tabletsare prepared according to the process set forth in Example 1.

In Example 6, 10 mg controlled release oxycodone hydrochloride tabletsare prepared according to the process set forth in Example 2.

Thereafter, dissolution studies of the tablets of Examples 5 and 6 areconducted at different pH levels, namely, pH 1.3, 4.56, 6.88 and 7.5.

The results are provided in Tables 9 and 10 below:

                  TABLE 9                                                         ______________________________________                                        Example 5                                                                     Percentage Oxycodone HCl 30 mg Tablets Dissolved Over Time                    pH   1        2      4     8    12     18    24                               ______________________________________                                        1.3  29.5     43.7   61.8  78.9 91.0   97.0   97.1                            4.56 34.4     49.1   66.4  82.0 95.6   99.4  101.1                            6.88 33.8     47.1   64.4  81.9 92.8   100.5 105.0                            7.5  27.0     38.6   53.5  70.0 81.8   89.7   96.6                            ______________________________________                                    

                  TABLE 10                                                        ______________________________________                                        Example 6                                                                     Percentage Oxycodone HCl - 10 mg Tablets Dissolved Over Time                  pH   1        2      4      8    12     18   24                               ______________________________________                                        1.3  25.9     41.5   58.5   73.5 85.3   90.7  94.2                            4.56 37.8     44.2   59.4   78.6 88.2   91.2 93.7                             6.88 34.7     45.2   60.0   75.5 81.4   90.3 93.9                             7.5  33.2     40.1   51.5   66.3 75.2   81.7 86.8                             ______________________________________                                    

EXAMPLES 7-12

In Examples 7-12, 4 mg and 10 mg oxycodone HCl tablets were preparedaccording to the formulations and methods set forth in the assignee'sU.S. Pat. No. 4,990,341.

In Example 7, oxycodone hydrochloride (10.00 gm) was wet granulated withlactose monohydrate (417.5 gm) and hydroxyethyl cellulose (100.00 gm),and the granules were sieved through a 12 mesh screen. The granules werethen dried in a fluid bed dryer at 50° C. and sieved through a 16 meshscreen.

Molten cetostearyl alcohol (300.0 gm) was added to the warmed oxycodonecontaining granules, and the whole was mixed thoroughly. The mixture wasallowed to cool in the air, regranulated and sieved through a 16 meshscreen.

Purified Talc (15.0 gm) and magnesium stearate (7.5 gm) were then addedand mixed with the granules. The granules were then compressed intotablets.

Example 8 is prepared in the same manner as Example 7; however, theformulation includes 10 mg oxycodone HCl/tablet. The formulas forExamples 7 and 8 are set forth in Tables 11 and 12, respectively.

                  TABLE 11                                                        ______________________________________                                        Formulation of Example 7                                                      Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          4.0      10.0                                              Lactose monohydrate                                                                              167.0    417.5                                             Hydroxyethylcellulose                                                                            40.0     100.0                                             Cetostearyl alcohol                                                                              120.0    300.0                                             Purified talc      6.0      15.0                                              Magnesium stearate 3.0      7.5                                               ______________________________________                                    

                  TABLE 12                                                        ______________________________________                                        Formulation of Example 8                                                      Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          10.0     25.0                                              Lactose monohydrate                                                                              167.0    417.5                                             Hydroxyethylcellulose                                                                            40.0     100.0                                             Cetostearyl alcohol                                                                              120.0    300.0                                             Talc               6.0      15.0                                              Magnesium stearate 3.0      7.5                                               ______________________________________                                    

In Example 9, 4 mg oxycodone HCl controlled release tablets are preparedaccording to the excipient formula cited in Example 2 of U.S. Pat. No.4,990,341. The method of manufacture is the same as set forth inExamples 7 and 8 above. Example 10 is prepared according to Example 9,except that 10 mg oxycodone HCl is included per tablet. The formulas forExamples 9 and 10 are set forth in Tables 13 and 14, respectively.

                  TABLE 13                                                        ______________________________________                                        Formulation of Example 9                                                      Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          4.0      10.0                                              Anhydrous Lactose  167.0    417.5                                             Hydroxyethylcellulose                                                                            30.0     75.0                                              Cetostearyl alcohol                                                                              90.0     225.0                                             Talc               6.0      15.0                                              Magnesium stearate 3.0      7.5                                               ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                        Formulation of Example 14                                                     Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          10.0     25.0                                              Hydrous lactose    167.0    417.5                                             Hydroxyethylcellulose                                                                            30.0     75.0                                              Cetostearyl alcohol                                                                              90.0     225.0                                             Talc               6.0      15.0                                              Magnesium stearate 3.0      7.5                                               ______________________________________                                    

In Example 11, oxycodone 4 mg controlled release tablets are preparedwith the same excipient formula cited in Example 3 of U.S. Pat. No.4,990,341.

Oxycodone hydrochloride (32.0 gm) was wet granulated with lactosemonohydrate (240.0 gm) hydroxyethyl cellulose (80.0 gm) and methacrylicacid copolymer (240.0 gm, Eudragit® L-100-55), and the granules weresieved through a 12 mesh screen. The granules were then dried in a FluidBed Dryer at 50° C. and passed through a 16 mesh screen.

The warmed oxycodone containing granules was added molten cetostearylalcohol (240.0 gm), and the whole was mixed thoroughly. The mixture wasallowed to cool in the air, regranulated and sieved through a 16 meshscreen. The granules were then compressed into tablets.

Example 12 is prepared in identical fashion to Example 11, except that10 mg oxycodone HCl is included per tablet. The formulations forExamples 11 and 12 are set forth in Tables 15 and 16, respectively.

                  TABLE 15                                                        ______________________________________                                        Formulation of Example 11                                                     Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          4.0      32.0                                              Lactose monohydrate                                                                              30.0     240.5                                             Hydroxyethylcellulose                                                                            10.0     80.0                                              Methacrylic acid copolymer                                                                       30.0     240.0                                             Cetostearyl alcohol                                                                              30.0     240.0                                             ______________________________________                                    

                  TABLE 16                                                        ______________________________________                                        Formulation of Example 12                                                     Ingredient         mg/tablet                                                                              g/batch                                           ______________________________________                                        Oxycodone hydrochloride                                                                          10.0     80.0                                              Lactose monohydrate                                                                              30.0     240.5                                             Hydroxyethylcellulose                                                                            10.0     80.0                                              Methacrylic acid copolymer                                                                       30.0     240.0                                             Cetostearyl alcohol                                                                              30.0     240.0                                             ______________________________________                                    

Next, dissolution studies were conducted on the tablets of Examples 7-12using the USP basket method as described in the U.S. Pharmacopoeia XXII(1990). The speed was 100 rpm, the medium was simulated gastric fluidfor the first hour followed by simulated intestinal fluid thereafter, ata temperature of 37° C. Results are given in Table 17.

                  TABLE 17                                                        ______________________________________                                        DISSOLUTION STUDIES OF EXAMPLES 7-12                                          Time  % Oxycodone Dissolved                                                   (hrs) Ex. 7  Ex. 8    Ex. 9                                                                              Ex. 10  Ex. 11                                                                              Ex. 12                               ______________________________________                                        1     23.3   25.5     28.1 29.3    31.3  40.9                                 2     35.6   37.5     41.5 43.2    44.9  55.6                                 4     52.9   56.4     61.2 63.6    62.1  74.2                                 8     75.3   79.2     83.7 88.0    82.0  93.9                                 12    90.7   94.5     95.2 100.0   91.4  100.0                                ______________________________________                                    

EXAMPLES 13-16 Clinical Studies

In Examples 13-16, randomized crossover bioavailability studies wereconducted employing the formulation of Examples 2 (organic manufacture)and 3 (aqueous manufacture).

In Example 13, a single dose fast/fed study was conducted on 24 subjectswith oxycodone tablets prepared according to Example 3.

In Example 14, a steady-state study was conducted on 23 subjects after12 hours with oxycodone tablets prepared according to Example 2, andcompared to a 5 mg oxycodone immediate-release solution.

In Example 15, a single dose study was conducted on 22 subjects usingoxycodone tablets prepared according to Example 3, and compared to a 20mg oxycodone immediate release solution.

In Example 16, a 12 subject single-dose study was conducted using 3×10mg oxycodone tablets prepared according to Example 3, and compared to a30 mg oxycodone immediate release solution.

The results of Examples 13-16 are set forth in Table 18.

                  TABLE 18                                                        ______________________________________                                                              AUC        Cmax  Tmax                                   Example   Dosage      ng/ml/hr   ng/ml hr                                     ______________________________________                                        13        10 mg CR Fast                                                                              63        6.1   3.8                                              10 mg CR Fed                                                                               68        7.1   3.6                                    14        5 mg IR q6h 121        17    1.2                                              10 mg CR ql2h                                                                             130        17    3.2                                    15        20 mg IR    188        40    1.4                                              2 × 10 mg CR                                                                        197        18    2.6                                    16        30 mg IR    306        53    1.2                                              3 × 10 mg CR                                                                        350        35    2.6                                              30 mg CR    352        36    2.9                                    ______________________________________                                         IR denotes immediaterelease oxycodone solution.                               CR denotes controlledrelease tablets                                     

EXAMPLE 17 Clinical Studies

In Example 17, a single dose, double blind, randomized study determinedthe relative analgesic efficacy, the acceptability, and relativeduration of action of an oral administration of controlled releaseoxycodone 10, 20 and 30 mg prepared according to the present invention(CR OXY) compared to immediate release oxycodone 15 mg (IR OXY),immediate release oxycodone 10 mg in combination with acetaminophen 650mg (IR OXY/APAP) and placebo in 180 patients with moderate or severepain following abdominal or gynecological surgery. Patients rated theirpain intensity and pain relief hourly for up to 12 hours postdosing.Treatments were compared using standard scales for pain intensity andrelief, and onset and duration of pain relief.

All active treatments were significantly superior to placebo for many ofthe hourly measures, and for sum pain intensity differences (SPID) andtotal pain relief (TOTPAR). A dose response was seen among the 3 doselevels of CR OXY for pain relief and peak pain intensity difference(PID), with CR OXY 20 mg and 30 mg being significantly better than the10 mg dose. IR OXY was significantly superior to CR OXY 10 mg at hr 1and 2. IR OXY/APAP was significantly superior to the 3 doses of CR OXYat hr 1, and to CR OXY 10 mg at hrs 2 through 5. Onset time wassignificantly shorter for the IR OXY and IR OXY/APAP treatment groups incomparison to the 3 CR OXY treatments. The distribution functions forduration of relief revealed significantly longer duration of relief forthe three CR OXY doses than for IR OXY and IR OXY/APAP. No seriousadverse experiences were reported. The results are more particularlyreported in Table 19 below.

                  TABLE 19                                                        ______________________________________                                        PATIENT DISPOSITION                                                           TREATMENT GROUP                                                                      IR OXY   CR OXY                                                               15   PLA-    10     20  30  2                                                 mg   CEBO    mg     mg  mg  PERC* TOTAL                                ______________________________________                                        Enrolled and                                                                           31     31      30   30  30  30    182                                Randomized                                                                    to Study                                                                      Treatment                                                                     Entered the                                                                            31     31      30   30  30  30    182                                Study Treat-                                                                  ment Phase                                                                    Completed                                                                              31     30      30   30  30  30    181                                the Study                                                                     Discontinued                                                                            0      1       0    0   0   0     1                                 from the Study                                                                Excluded from                                                                 Efficacy                                                                      Analysis                                                                      Vomited   0      1       0    0   0   0     1                                 prior to                                                                      1 hr post dose                                                                Inadvertently                                                                           1      0       0    0   0   0     1                                 received                                                                      rescue during                                                                 study                                                                         Analysis                                                                      Population:                                                                   Evaluable for                                                                          30     30      30   30  30  30    180                                Safety and                                                                    Efficacy                                                                      Evaluable for                                                                          31     31      30   30  30  30    182                                Safety                                                                        ______________________________________                                         *2 tablets of Percocet                                                   

The time-effect curves for pain intensity, pain intensity differencesand pain relief are shown in FIGS. 1-4. CR OXY 10 mg had significantly(p<0.05) lower pain intensity scores than the placebo-treated patientsat hours 3-11 and lower pain scores than IR OXY 15 mg and Percocet® athour 10. CR OXY 20 mg has significantly (p<0.05) lower pain intensityscores compared to placebo at hours 2-11 and significantly (p<0.05)lower pain scores than CR OXY 10 mg, IR OXY 15 mg and Percocet at hours9-11. CR OXY 30 mg had significantly (p<0.05) lower pain scores thanplacebo at hours 2-11 and lower pain scores than CR OXY 10 mg at hours2, 3, and 5 and lower scores than Percocet® at hour 10.

For hourly pain relief scores categorical and visual analog scales (CATand VAS), CR OXY 10 mg had significantly (p<0.05) higher pain reliefscores than placebo at hours 3-11 and higher relief scores than IR OXYand Percocet® at hour 10 (and Percocet® at hour 11). CR OXY 20 mg hadsignificantly (p<0.05) higher relief scores than placebo at hours 2-12and higher relief scores than Percocet® at hours 9-12. In addition, CROXY had significantly (p<0.05) higher pain relief than IR OXY at hours10-12. CR OXY 30 mg had significantly (p<0.05) higher pain relief scoresthan placebo at hours 2-12 and higher scores than Percocet® at hours9-12 and IR OXY 15 mg at hour 10.

Each treatment group was significantly (p<0.05) better than placebo withrespect to the sum of the pain intensity differences (SPID) and totalpain relief (TOTPAR).

Duration of pain relief as measured by the patient stopwatch methodshowed that CR OXY 10 mg, 20 mg and 30 mg had significantly (p<0.05)longer duration of action compared to IR OXY 15 mg and 2 tabletsPercocet®. In addition, the three controlled-release formulations hadsignificantly (p<0.05) longer times to remedication compared toPercocet®.

Before remedication, a total of 104 (57%) of patients reported 120adverse experiences. The most common were somnolence, fever, dizzinessand headache.

Based upon the results of this study it is concluded that the controlledrelease oxycodone formulations of the present invention relieve moderateto severe post-operative pain, e.g., due to abdominal or gynecologicalsurgery in women. There is a dose response noted in which placebo<10mg<20 mg<30 mg CR OXY following a single dose. Onset of action occurredin one hour with peak effects noted from 2 to 5 hours and a duration ofeffect from 10 to 12 hours. In the chronic pain situation steady statedosing may prolong this effect. Side effects are expected and easilymanaged. Headache may be related to dose. Dizziness and somnolence werereported.

IR OXY 15 mg has an intermediate peak effect compared to controlledrelease oxycodone. Its duration of action is shorter (6-8 hours).Percocet® is quite effective in terms of onset, peak effect and safety.The duration of action is 6-8 hours.

In summary, CR OXY was clearly an effective oral analgesic, with aslower onset but a longer duration of effect than either IR OXY or IROXY/APAP.

EXAMPLE 18 Clinical Studies

In Example 18, a steady state crossover trial was conducted in 21 normalmale subjects comparing

a. CR OXY 10 mg administered every 12 hours (q12h); and

b. Roxicodone® oral solution 5 mg (ROX) administered every 6 hours(q6h),

Treatment (b) was the study reference standard. The average age was 34years, height 176 cm and weight 75 kg. No unusual features were notedabout the group.

FIG. 5 shows the mean plasma oxycodone concentrations for the twoformulations over the 12 hour dosing interval. The results aresummarized in Table 18 in terms of mean values, ratios of mean valuesand 90% confidence intervals.

As inspection of Table 18 reveals, with one exception, no significantdifferences were detected between the two formulations. The singleexception is the mean t_(max) for CR OXY of 3.18 hours which, asexpected for a controlled release formulation, significantly exceededthe ROX mean of 1.38 hours. Mean AUC-based bioavailability, (ROX=100%)was 104.4% with 90% confidence limits of 90.9 to 117.9%. Thus, the FDAspecification of ±20% is met so that the study results support anassertion of equal oxycodone availability.

                  TABLE 20                                                        ______________________________________                                        SUMMARY OF PHARMACOKINETIC PARAMETERS                                         FOR OXYCODONE FOLLOWING A SINGLE DOSE OF                                      CR OXY (10 mg q12H) AND ROXIDODONE ®                                      ORAL SOLUTION (5 mg g6h)                                                                          ROXI-                                                                         CODONE     OXY/                                           PARA-       CR      SOLU-      ROXI  90%                                      METER       OXY     TION       (%)   CI*                                      ______________________________________                                        C.sub.max (ng/mL)                                                             ARITH.      15.11   15.57      97.08 85.59-                                   MEAN(SD)    (4.69)  (4.41)           108.50                                   GEOMETRIC   14.43   15.01      95.14                                          MEAN                                                                          C.sub.min (ng/mL)                                                             ARITH.      6.24    6.47       96.41 80.15-                                   MEAN(SD)    (2.64)  (3.07)           112.74                                   GEOMETRIC   5.62    5.83       96.48                                          MEAN                                                                          t.sub.max (hrs)                                                               ARITH.      3.18    1.38       230.17                                                                              160.71-                                  MEAN(SD)    (2.21)  (0.71)*          298.71                                   AUC(0-12 hrs)                                                                 ARITH.      103.50  99.10      104.44                                                                              90.92-                                   MEAN(SD)    (40.03) (35.04)          117.94                                   GEOMETRIC   97.06   93.97      103.29                                         MEAN                                                                          % Swing                                                                       ARITH.      176.36  179.0      98.53 62.06-                                   MEAN(SD)    (139.0) (124.25)         134.92                                   % Fluctuation                                                                 ARITH.      108.69  117.75     92.22 76.81-                                   MEAN(SD)    (38.77) (52.47)          107.57                                   End Point                                                                     ARITH.      -1.86   -1.86      99.97 117.77-                                  MEAN(SD)    (2.78)  (2.19)           22.23                                    ______________________________________                                         *90% Confidence Interval                                                      Significant Difference p < 0.05                                          

EXAMPLE 19 Clinical Studies

In Example 19, twenty-four normal, healthy male subjects were enrolledin a randomized single-dose two-way crossover study to compare theplasma oxycodone concentrations obtained after dosing with twocontrolled-release oxycodone 10 mg tablets versus 20 mg (20 ml of 5 mg/5ml) of immediate release (IR) oxycodone hydrochloride solution.Twenty-three subjects completed the study and were eligible foranalysis.

Plasma oxycodone concentrations were determined by a high performanceliquid chromatographic procedure. Arithmetic Mean C_(max), t_(max), AUC,and half-lives calculated from individual plasma oxycodoneconcentration-versus-time data are set forth in Table 21:

                  TABLE 21                                                        ______________________________________                                                Reference   Test Pro-                                                 Pharmaco-                                                                             Product     duct CR Oxy-  90%                                         kinetic IR Oxyco-   codone 2 ×                                                                            Confidence                                  Parameter                                                                             done 20 mg  10 mg F. ∘  (%)                                                                 Interval                                    ______________________________________                                        C.sub.max                                                                             41.60       18.62   44.75   32.5-                                     (ng/ml)                             57.0                                      t.sub.max                                                                             1.30        2.62    200.83  169.8-                                    (hours)                             232.6                                     AUC     194.35      199.62  102.71  89.5-                                     (0-36)                              115.9                                     (mg × hr/ml)                                                            AUC (0-∞)                                                                       194.38      208.93  107.49  92.9-                                     (ng × hr/ml)                  121.9                                     t.sub.1/2 (elim)                                                                      3.21        7.98*   249.15  219.0-                                    (hrs)                               278.8                                     t.sub.1/2 (abs)                                                                       0.35        0.92*   264.17  216.0-                                    (hrs)                               310.7                                     ______________________________________                                         F ∘ (%) = Oral bioavailability (CR oxycodone 2 × 10         mg/IR oxycodone 20 mg)                                                        *Statistically significant (p = 0.0001)                                  

For C_(max), t_(max), t_(1/2) (elim) and t_(1/2) (abs) there werestatistically significant differences between the CR OXY and IR OXY.There were no statistically significant differences between the twotreatments in the extent of absorption [AUC (0,36), AUC (0,∞)]. The 90%confidence interval for CR OXY relative to IR OXY relative was89.5%-115.9% for AUC (0,36) and 92.9%-121.9% for AUC (0,∞). Based on the90% confidence interval analysis, the controlled-release oxycodonetablets were equivalent in extent of absorption (AUC 0,36) to theimmediate-release oxycodone solution. The controlled-release oxycodoneabsorption was slower by approximately 1.3 hours. No statisticallysignificant differences were noted between the two treatments withreference to adverse experiences, none of which were consideredclinically unusual for opiates for this type of study.

The above studies demonstrate a significant dose-response relationshiputilizing the controlled release oxycodone formulations of the presentinvention at dosages of 10, 20 and 30 mg which does not deviate fromparallelism with dose-response slopes for MS Contin in similarlydesigned well-controlled analgesic efficacy studies of MS Continreported by Kaiko R. S., Van Wagoner D., Brown J., et al.,"Controlled-Release Oral Morphine (MS Contin® Tablets, MSC) inPostoperative Pain.", Pain Suppl., 5:S149 1990, who compared 30, 60, 90,and 120 mg of MS Contin as compared with 10 mg of intramuscular morphineand placebo and Bloomfield, et al., "Analgesic Efficacy and Potency ofTwo Oral Controlled-Release Morphine Preparations", ClinicalPharmacology & Therapeutics, (in press), who compared 30 and 90 mg of MSContin as compared to 30 and 90 mg of another controlled-release oralmorphine preparation, Oramorph SR 30 mg tablets.

The examples provided above are not meant to be exclusive. Many othervariations of the present invention would be obvious to those skilled inthe art, and are contemplated to be within the scope of the appendedclaims.

What is claimed is:
 1. A controlled release oxycodone formulation fororal administration to human patients, comprising from about 10 mg toabout 160 mg oxycodone, based on the hydrochloride salt, saidformulation providing a mean maximum plasma concentration of oxycodonefrom about 6 to about 240 ng/ml from a mean of about 2 to about 4.5hours after administration and a mean minimum plasma concentration ofoxycodone from about 3 to about 120 ng/ml from about 10 to about 14hours after administration every 12 hours after repeated dosing throughsteady state conditions, wherein said formulation provides pain reliefin said patient for at least 12 hours after administration.
 2. Thecontrolled release oxycodone formulation of claim 1, comprising fromabout 10 to about 40 mg oxycodone based on the hydrochloride salt, saidformulation providing a mean maximum plasma concentration of oxycodonefrom about 6 to about 60 ng/ml from a mean of about 2 to about 4.5 hoursafter administration.
 3. The controlled release oxycodone formulation ofclaim 1, comprising from about 40 mg to about 160 mg oxycodone based onthe hydrochloride salt, said formulation providing a mean maximum plasmaconcentration of oxycodone from about 60 to about 240 ng/ml from a meanof about 2 to about 4.5 hours after administration.
 4. The solidcontrolled release oxycodone formulation of claim 1, comprisingoxycodonehydrochloride dispersed in an effective amount of a controlled releasematrix selected from the group consisting of hydrophilic polymers,hydrophobic polymers, digestible substituted or unsubstitutedhydrocarbons having from about 8 to about 50 carbon atoms, polyalkyleneglycols, and mixtures of any of the foregoing, and a suitable amount ofa suitable pharmaceutical diluent.
 5. The solid controlled releaseoxycodone formulation of claim 1, comprising:(a) an analgesicallyeffective amount of spheroids comprising oxycodone or a salt thereof andeither a spheronising agent or an acrylic polymer or copolymer, suchthat the total dosage of oxycodone in said dosage form is from about 10to about 160 mg based on the hydrochloride salt; and (b) a film coatingon said spheroids which controls the release of the oxycodone oroxycodone salt at a controlled rate in an aqueous medium, wherein saidcomposition provides an in vitro dissolution rate of the dosage form. 6.The controlled release oxycodone formulation of claim 1, comprising atablet wherein said oxycodone is dispersed in a controlled releasematrix.
 7. The controlled release oxycodone formulation of claim 1,wherein said oxycodone is in the form of the hydrochloride salt.
 8. Amethod for substantially reducing the range in daily dosages required tocontrol pain in human patients, comprising administering to a humanpatient an oral controlled release dosage formulation comprising fromabout 10 to about 160 mg oxycodone or a salt thereof based on thehydrochloride salt which provides a mean maximum plasma concentration ofoxycodone form about 6 to about 240 ng/ml from a mean of about 2 toabout 4.5 hours after administration and a mean minimum plasmaconcentration of oxycodone from about 3 to about 120 ng/ml from about 10to about 14 hours after administration every 12 hours after repeateddosing through steady state conditions, wherein said formulationprovides pain relief in said patient for at least 12 hours afteradministration.
 9. A method for substantially reducing the range indaily dosages required to control pain in substantially all humanpatients, comprising administering to a human patient an oral solidcontrolled release dosage formulation comprising from about 10 mg toabout 40 mg oxycodone or a salt thereof based on the hydrochloride saltwhich provides a mean maximum plasma concentration of oxycodone fromabout 6 to about 60 ng/ml from a mean of up to about 2 to about 4.5hours after administration and a mean minimum plasma concentration ofoxycodone from about 3 to about 30 ng/ml from about 10 to about 14 hoursafter administration every 12 hours after repeated dosing through steadystate conditions, wherein said formulation provides pain relief in saidpatient for at least 12 hours after administration.
 10. A method forsubstantially reducing the range in daily dosages required to controlpain in substantially all human patients, comprising administering to ahuman patient an oral solid controlled release dosage formulationcomprising from about 40 mg to about 160 mg oxycodone or a salt thereofbased on the hydrochloride salt which provides a mean maximum plasmaconcentration of oxycodone from about 60 to about 240 ng/ml from a meanof up to about 2 to about 4.5 hours after administration and a meanminimum plasma concentration of oxycodone from about 30 to about 120ng/ml from about 10 to about 14 hours after administration afterrepeated dosing every 12 hours through steady state conditions, whereinsaid formulation provides pain relief in said patient for at least 12hours after administration.